Biochemistry

阮雪芬Sep 9, 2002

NTUT

Chapter 1. Introduction

History What is biochemistry Biochemistry and life Biochemical Energy Transfer of Information from DNA to

Protein

History

Life: 150 years ago Biochemistry: 60 years ago

What is Biochemistry

?

Definition

The science that is concerned with the structures, interactions, and transformations of biological molecules

The chemistry of life

Biochemistry can be subdivided three principal areas

Structural chemistry Metabolism The chemistry of processes and

substances that store and transmit biological information (molecular genetics)

Biochemistry and Life

The cell is the fundamental unit of life Prokaryotes and eukaryotes Eukaryotic cells

• animal cells

• plant cells (chloroplasts and cell walls)

Biochemistry and Life

Cells are composed of:• Small molecules

• Macromolecules

• organelles

Biochemistry and LifePercent of Total Cell Weight

Number of Types of Each Molecules

Water 70 1

Inorganic ions 1 20

Sugars and precursors 3 200

Amino acids and precursors

0.4 100

Nucleotides and precursors

0.4 200

Lipids and precursors 2 50

Other small molecules 0.2 ~200

Macromolecules 22 ~5000

The Approximate Chemical Composition of Bacterial Cell

Biochemistry and Life

Expect for water, most of the molecules found in the cell are macromolecules, can be classified into four different categories:• Lipids

• Carbohydrates

• Proteins

• Nucleic acids

Biochemistry and Life

Lipids are primarily hydrocarbon structures Carbohydrates, like lipids, contain a carbon

backbone, but they also contain many polar hydroxyl (-OH) groups and therefore very soluble in water.

Proteins are the most complex macromolecules in the cell. They are composed of linear polymers called polypeptides, which contain amino acids connected by peptide bonds.

Lipid Structure

Carbohydrates Structure

Biochemistry and Life

Each amino acid contains a central carbon atom attached to four substituents• A carboxyl group

• An amino group

• A hydrogen atom

• An R group Nucleic acids are the large macromolecules in

the cells. They are very long linear polymers, called polynucleotides, composed of nucleotides.

Amino Acids Structures

Biochemistry and Life

A nucleotide contains :• A five-carbon sugar molecules

• One or more phosphate groups

• A nitrogenous base

DNA: A, T, G, C RNA: A, U, G,C

DNA Contain Four Bases

RNA

Covalent Structure of DNA

Watson-Crick base pairs

Watson-Crick base pairs

The Double Helix

Biochemical Energy All cellular functions re quire energy. The most-important chemical form of

energy in most cells is ATP, adenosine 5’-triphosphate.

ATP ADP + Pi

Most ATP synthesis occurs in chloroplasts and mitochondria

ADT and ATP Structures

Energy Transfer

Energy Transfer

Transfer of Information from DNA to Protein

DNA

RNA

Protein

Transfer of Information from DNA to Protein